Information processing apparatus, control method for information processing apparatus, and storage medium

ABSTRACT

An information processing apparatus includes a plurality of processing modules that are connected to each other on a ring bus, a connector for optionally attaching to an extension processing unit, a detection unit configured to detect attachment of the extension processing unit to the connector, and a bus switching unit configured to change, in a case where the detection unit detects the attachment of the extension processing unit, a path of the ring bus in such a manner that an extension processing module in the extension processing unit is connected.

BACKGROUND OF THE INVENTION

Field of the Invention

One disclosed aspect of the embodiments relates to an informationprocessing apparatus in which a bus structure can be changed, and to acontrol method for the information processing apparatus.

Description of the Related Art

A ring bus is known as a bus structure, of transmitting data in a singledirection, in which a plurality of modules is connected to buses forminga ring shape. In some cases, the structure of the ring bus needs to bechanged.

As a conventional method of changing the ring bus structure, a methoddiscussed in Japanese Patent Application Laid-Open No. 2011-8541 isknown as the method, of changing the ring bus structure, in which amaster module outputs data for changing the bus structure to a datatransmission path, and the bus structure is changed in a slave module.

More specifically, Japanese Patent Application Laid-Open No. 2011-8541discusses a structure in which a plurality of modules is connected toeach other in a ring form via a plurality of paths, and processing isexecuted in a manner such that the path of the ring bus is switched inaccordance with data input. This method discussed in Japanese PatentApplication Laid-Open No. 2011-8541 is for a configuration in which thepath of the ring bus is to be selected for connecting required modulesin the plurality of modules provided in advance. Therefore, a new modulecannot be added once the structure is established.

Thus, a ring bus structure, having a configuration in which a functionof an image forming apparatus is extended with a module which isconnected to a ring bus via a connector, has been desired to be capableof easily changing the ring bus in both of a case where a new module isconnected via the connector and a case where a module is not connected.

SUMMARY OF THE INVENTION

According to an aspect of the embodiments, an information processingapparatus includes a plurality of processing modules that are connectedto each other on a ring bus, a connector for optionally attaching to anextension processing unit, a detection unit configured to detectattachment of the extension processing unit to the connector, and a busswitching unit configured to change, in a case where the detection unitdetects the attachment of the extension processing unit, a path of thering bus in such a manner that an extension processing module in theextension processing unit is connected.

Further features of the disclosure will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating a configuration of an imageforming apparatus according to an exemplary embodiment.

FIGS. 2A and 2B are diagrams each illustrating a configuration of animage processing unit according to the exemplary embodiment.

FIG. 3 is a block diagram illustrating a configuration of an imageforming apparatus according to another exemplary embodiment.

FIG. 4 is a diagram illustrating a configuration of an image processingunit according to another exemplary embodiment.

FIG. 5 is a diagram illustrating a configuration of a controller unitaccording to still another exemplary embodiment.

FIG. 6 is a block diagram illustrating a configuration of an imageforming apparatus according to yet still another exemplary embodiment.

FIG. 7 is a diagram illustrating a configuration of an image processingunit according to yet still another exemplary embodiment.

FIG. 8 is a flowchart illustrating processing executed, when licenseinformation is input, by a control unit according to yet still anotherexemplary embodiment.

FIG. 9 is a flowchart illustrating processing, for a bus switchingregister unit, executed by the control unit according to yet stillanother exemplary embodiment.

FIG. 10 is a flowchart illustrating processing, for a bus switchingregister unit, executed by a control unit according to further yet stillanother exemplary embodiment.

DESCRIPTION OF THE EMBODIMENTS

Exemplary embodiments of an information processing apparatus aredescribed below with reference to the drawings, by taking an imageforming apparatus as an example of the information processing apparatus.

<Configuration of Image Forming Apparatus>

FIG. 1 is a block diagram illustrating a configuration of an imageforming apparatus 100 according to a first exemplary embodiment.

The image forming apparatus 100 includes a controller unit 110, a harddisk drive (HDD) 160, an operation unit 350, a scanner unit 300, and aprinting unit 400.

The controller unit 110 is in charge of the entire control in the imageforming apparatus 100. The controller unit 110 includes a control unit120, a random access memory (RAM) 130, a read only memory (ROM) 140, anHDD I/F control unit 150, an image processing unit 170, and an extensionconnector 180.

The control unit 120 controls, based on a program in the ROM 140, thecomponents in the controller unit 110 as well as the operation unit 350,the scanner unit 300, and the printing unit 400.

The RAM 130 functions as, for example, a work area for an operation ofthe control unit 120.

The ROM 140 stores therein the program which is used by the control unit120.

The HDD I/F control unit 150 is connected to the control unit 120 via abus 200 and is further connected to the HDD 160 via a bus 240. Thecontrol unit 120 can store data in the HDD 160 and can read the datastored in the HDD 160, via the HDD I/F control unit 150.

The HDD 160 is a nonvolatile storage device that stores therein data. Astorage device (for example, a solid-state drive (SSD)) other than theHDD 160 may be employed.

The image processing unit 170 executes image processing on read imagedata input from the scanner unit 300 so that image data suitable for theprinting unit 400 is obtained.

The extension connector 180 is a connector to which an extensionprocessing unit 600 is attached. The extension processing unit 600 addsa function to the image forming apparatus 100.

The operation unit 350 provides various types of information to a uservia a display, and receives various instructions from the user using abutton and the like.

The scanner unit 300 reads a document, and inputs image data.

The printing unit 400 prints the image data obtained as a result of theimage processing which is executed by the image processing unit 170 onthe image data input from the scanner unit 300.

The control unit 120, the RAM 130, the ROM 140, the HDD I/F control unit150, the image processing unit 170, the operation unit 350, the scannerunit 300, and the printing unit 400 are connected to each other via thebus 200.

The image processing unit 170 is connected to the extension connector180 via an output ring bus 210 and an input ring bus 220, and is input aring bus switching signal 230. The output ring bus 210 and the inputring bus 220 are buses each of which includes a data signal, a clocksignal, and a strobe signal.

FIGS. 2A and 2B are diagrams each illustrating a configuration of theimage processing unit 170. FIG. 2A is a diagram illustrating aconfiguration in which the extension processing unit 600 is notconnected to the extension connector 180. FIG. 2B is a diagramillustrating a configuration in which the extension processing unit 600is connected to the extension connector 180.

The image processing unit 170 includes an input/output control unit 500,an image processing module A 510, an image processing module B 520, animage processing module C 530, and a bus switching unit 540.

The input/output control unit 500 is connected to the control unit 120via the bus 200. Upon receiving a control command issued from thecontrol unit 120 in accordance with the program stored in the ROM 140,the input/output control unit 500 controls the image processing module A510 in accordance with the received control command.

The image processing module A 510, the image processing module B 520,and the image processing module C 530 are modules each of which executesimage processing on image data transmitted by the control unit 120 tothe image processing unit 170.

The bus switching unit 540 is a switching circuit that switches a pathof a ring bus. More specifically, the bus switching unit 540 switches abus to be connected to a bus which inputs to the image processing moduleA 510 between a bus 260 and a bus 270 according to a bus switchingsignal 290. The bus switching signal 290 inputs to a terminal for thering bus switching signal 230. The logic level of the ring bus switchingsignal 230 of when the extension processing unit 600 is not attached tothe extension connector 180 depends on processing executed on the ringbus switching signal 230 (for example, a low level when pull downprocessing has been executed on the ring bus switching signal 230). Whenthe extension processing unit 600 is attached to the extension connector180, the ring bus switching signal 230is to be an output value of a bussetting unit 640. The logic level of the output value of the bus settingunit 640 is opposite to that of the ring bus switching signal 230.

The ring bus in the image processing unit 170 includes the bus 240, abus 250, the bus 260, and a bus 280. The image processing module A 510,the image processing module B 520, and the image processing module C 530are connected to each other on the ring bus. In the ring bus, image dataand setting data to be set on the image processing module A 510, theimage processing module B 520, and the image processing module C 530 aretransmitted in a single direction.

The bus 260 is connected to the output ring bus 210.

The bus switching unit 540 is connected to the bus 260 and also isconnected to the bus 270, and is input the bus switching signal 290.Further, the bus 270 is connected to the input ring bus 220, and the busswitching signal 290 inputs to the terminal for the ring bus switchingsignal 230.

In such a state, the bus switching unit 540 connects the bus 260 to thebus 280 based on the logic level of the bus switching signal 290.

The ring bus extending outside the image processing unit 170 includesthe bus 240, the bus 250, the bus 260, the output ring bus 210, a bus620, a bus 630, the input ring bus 220, the bus 270, and the bus 280. Insuch a state illustrated in FIG. 2B, the bus 270 is connected to the bus280 by the bus switching unit 540 based on the logic level of the busswitching signal 290.

The extension processing unit 600 includes an image processing chip 610and the bus setting unit 640. The image forming apparatus 100 isprovided with a new function when the extension processing unit 600 isattached.

The image processing chip 610 is a processing module having a newfunction of executing image processing on image data that is differentfrom those executed by the image processing module A 510, the imageprocessing module B 520, and the image processing module C 530.

The extension processing unit 600 is an option unit that can be attachedbased on the user's request.

The bus setting unit 640 outputs a signal, for switching the bus to beconnected to the bus 280 from the bus 260 to the bus 270, to the busswitching unit 540. In a case where the processing executed on the ringbus switching signal 230 is changed to the pull down processing and thelogic level of the ring bus switching signal 230 is set to low, The bussetting unit 640 is connected to a power supply via a resistor (notillustrated). The logic level of the ring bus switching signal 230 isset to high when the extension processing unit 600 is connected.

<Operation: when Extension Processing Unit 600 is not Connected>

Next, how the setting of the ring bus is switched when the extensionprocessing unit 600 is attached to the image processing unit 170 isdescribed.

An operation in a state as illustrated in FIG. 2A where the extensionprocessing unit 600 is not connected is described. In this state, thering bus is formed with the bus 240, the bus 250, the bus 260, and thebus 280 connected in series in this order by the bus switching unit 540.The image processing module A 510, the image processing module B 520,and the image processing module C 530 are connected to each other on thering bus.

Since the pull down processing has been executed on the ring busswitching signal 230, the logic level of the ring bus switching signal230 is at the low level. The ring bus switching signal 230 is thus inputto the bus switching unit 540 as the bus switching signal 290.

Because the ring bus switching signal 230 thus input is at the lowlevel, the bus switching unit 540 selects the bus 260 as the busconnected to the bus 280.

<Operation: Switching Operation to State where Extension Processing Unit600 is Connected>

Next, a switching operation to a state as illustrated in FIG. 2B wherethe extension processing unit 600 is connected is described. The bussetting unit 640 in the extension processing unit 600 outputs the ringbus switching signal 230, for switching the bus connected to the bus 280from the bus 260 to the bus 270, to the bus switching unit 540.

When the extension processing unit 600 is connected to the extensionconnector 180, the output from the bus setting unit 640 causes the logiclevel of the ring bus switching signal 230 to be set to high.

The bus switching unit 540 that has received the ring bus switchingsignal 230 switches the bus to be connected to the bus 280 from the bus260 to the bus 270.

Thus, the bus 240, the bus 250, the bus 260, the output ring bus 210,the bus 620, the bus 630, the input ring bus 220, and the bus 270, bus280 are connected to each other, whereby the ring bus extending outsideis formed.

The image processing module A 510, the image processing module B 520,the image processing module C 530, and the image processing chip 610 ofthe extension processing module are connected to each other on the outerring bus.

In the first exemplary embodiment described above, the ring busstructure can be changed in a manner such that the bus switching unit540 switches, based on the output from the bus setting unit 640 providedin the extension processing unit 600, the bus to be connected to the bus280 from the bus 260 to the bus 270. With the new ring bus structurethus established, the image processing chip 610 provided in theextension processing unit 600 can be added to the ring bus of the imageprocessing unit 170 so that a new function can be provided.

In the first exemplary embodiment, the ring bus switching signal 230 isused for changing the path of the ring bus. In a second exemplaryembodiment, the path of the ring bus is changed in accordance with asignal of a bus on the ring bus.

FIG. 3 is a block diagram illustrating a configuration of an imageforming apparatus 105 according to the second exemplary embodiment.

The configuration of the image forming apparatus 105 is the same as thatof the image forming apparatus 100 except that the image formingapparatus 105 includes a controller unit 115 instead of the controllerunit 110.

The configuration of the controller unit 115 is the same as that of thecontroller unit 110 except that the controller unit 115 is provided withan image processing unit 800. The image processing unit 800 is connectedto the extension connector 180 via the output ring bus 210 and the inputring bus 220. The image processing unit 800 according to the secondexemplary embodiment has no terminal for receiving the ring busswitching signal 230.

FIG. 4 is a diagram illustrating a configuration of the image processingunit 800 according to the second exemplary embodiment.

The configuration of the image processing unit 800 is the one in which aclock detection unit 700 is added to the configuration of the imageprocessing unit 170.

The clock detection unit 700 detects a clock signal on the input ringbus 220. Upon detecting the input of the clock signal, the clockdetection unit 700 generates the bus switching signal 290 for changingthe bus connected to the bus 280 from the bus 260 to the bus 270, andoutputs the bus switching signal 290 to the bus switching unit 540.

In the example described in the second exemplary embodiment, the busswitching signal 290 for causing the bus switching unit 540 to performthe switching is generated when the input of the clock signal on thering bus is detected. According to the second exemplary embodiment,there can be provided an advantageous effect that even without anadditional signal terminal in the image processing unit, the path of thering bus can be changed.

In the first and the second exemplary embodiments, the bus switchingunit is provided in the image processing unit. In a third exemplaryembodiment, the bus switching unit is provided outside the imageprocessing unit.

FIG. 5 is a diagram illustrating a configuration of a controller unit118 according to the third exemplary embodiment. The controller unit 118is different from the controller unit 110 according to the firstexemplary embodiment and the controller unit 115 according to the secondexemplary embodiment in that a bus switching unit 910 is providedoutside an image processing unit 900.

The bus switching unit 910 switches, based on the ring bus switchingsignal 230, the path for inputting a ring bus signal to the imageprocessing unit 900, between the path via the output ring bus 210 andthe path via the input ring bus 220.

According to the third exemplary embodiment, even though a ring busswitching unit is not provided inside the image processing unit 900, thebus switching unit 910 is provided outside the image processing unit 900whereby the ring bus can be formed with no extension processing unitattached to the extension connector 180. When the extension processingunit 600 is connected, the ring bus including the extension processingunit 600 can be formed with the bus switching unit 910 provided outsidethe image processing unit 900.

In the configurations described in the first and the second exemplaryembodiments, the bus switching unit is provided in the image processingunit. In the configuration described in the third exemplary embodiment,the bus switching unit is provided outside the image processing unit. Ina configuration described in a fourth exemplary embodiment, the busswitching unit is provided inside the image processing unit and iscontrolled by the control unit 120.

FIG. 6 is a block diagram illustrating a configuration of an imageforming apparatus 106 according to the fourth exemplary embodiment.

The configuration of the image forming apparatus 106 is the same as theconfiguration of the image forming apparatus 100 except that the imageforming apparatus 106 includes a controller unit 116.

The configuration of the controller unit 116 is the same as that of thecontroller unit 115 except that the controller unit 116 includes animage processing unit 860 and a license information storage unit 870.The image processing unit 860 is connected to the extension connector180 via the output ring bus 210 and the input ring bus 220. Whereasinput and output signals of the image processing unit 860 according tothe fourth exemplary embodiment are the same as those of the imageprocessing unit 800 according to the second exemplary embodiment, theimage processing unit 860 according to the fourth exemplary embodimenthas an internal block different from that in the second exemplaryembodiment.

The license information storage unit 870 is a nonvolatile memory thatstores therein license information. An initial value in the licenseinformation storage unit 870 is “0”. When connecting the extensionprocessing unit 600 to the extension connector 180 of the controllerunit 116, the user inputs license information through the operation unit350, so that the extension processing unit 600 can be used in the imageforming apparatus 106. Upon detecting the input of the licenseinformation, the control unit 120 writes “1” to the license informationstorage unit 870. When the user deletes the license information, thecontrol unit 120 writes “0” to the license information storage unit 870.Although, according to the fourth exemplary embodiment, the licenseinformation storage unit 870 is provided in the controller unit 116, thelicense information may be stored in the HDD 160. Alternatively, if theROM 140 is a readable-writable memory, the license information may bestored in the ROM 140.

FIG. 7 is a diagram illustrating a configuration of the image processingunit 860 according to the fourth exemplary embodiment.

The configuration of the image processing unit 860 is the one in whichthe clock detection unit 700 is replaced with a bus switching settingregister unit 760 in the configuration of the image processing unit 800.

The control unit 120 sets a register value in the bus switching settingregister unit 760 via the input/output control unit 500. The initialvalue in the bus switching setting register unit 760 is “0”. In thisstate, the bus switching signal 290 is at the low level. In a case wherethe value of the bus switching setting register unit 760 is “0” and thebus switching signal 290 is thus at the low level, the bus switchingunit 540 sets the bus 260 as the bus connected to the bus 280. When thecontrol unit 120 writes “1” to the bus switching setting register unit760 via the input/output control unit 500, the bus switching settingregister unit 760 outputs the bus switching signal 290 at the highlevel. When the bus switching signal 290 is at the high level, the busswitching unit 540 changes the bus connected to the bus 280 from the bus260 to the bus 270.

FIG. 8 is a flowchart illustrating processing executed by the controlunit 120 when the license information is input according to the fourthexemplary embodiment. In step S101, the control unit 120 executesprocessing of detecting the input of the license information by the userthrough the operation unit 350, for making the extension processing unit600 usable in the image forming apparatus 106. When the user inputs thelicense information through the operation unit 350, the control unit 120acquires the license information through the bus 200.

In step S102, the control unit 120 executes processing of acquiringcorrect license information that has been stored in advance in anonvolatile memory, such as the HDD 160 or the ROM 140.

In step S103, the control unit 120 checks whether the licenseinformation that has been input is correct, by comparing the licenseinformation that has been input with the license information read fromthe nonvolatile memory, such as the HDD 160 or the ROM 140. In a casewhere the control unit 120 determines that the input license informationis correct (YES in step S103), the processing proceeds to step S104.When the control unit 120 determines that the input license informationis incorrect in step S103 (NO in step S103), the processing proceeds tostep S106.

In step S104, the control unit 120 writes “1” to the license informationstorage unit 870.

In step S105, the control unit 120 issues a restart command. In responseto the control unit 120 issuing the restart command, the imageprocessing unit 860 and the HDD I/F control unit 150 in the controllerunit 116, the operation unit 350, the scanner unit 300, and the printingunit 400 are reset. At the same time, the control unit 120 starts aninitialization sequence so that the image forming apparatus 106 isrestarted.

In step S106, the control unit 120 issues an incorrect license displaycommand to the operation unit 350. The operation unit 350 that hasreceived the command displays a message on a display unit (notillustrated). The message thus displayed on the display unit (notillustrated) is a message notifying the user of the fact that the inputlicense information is incorrect, and prompting the user to inputlicense information again.

FIG. 9 is a flowchart illustrating processing for the bus switchingsetting register unit 760 executed by the control unit 120 according tothe fourth exemplary embodiment.

The processing illustrated in FIG. 9 is executed by the control unit 120in accordance with a program stored in the ROM 140, at the time of whenthe system of the controller unit 116 is started.

In step S201, the control unit 120 reads a value in the licenseinformation storage unit 870. In step S202, the control unit 120determines whether the value read in step S201 is “1”. In a case wherethe control unit 120 determines that the value read from the licenseinformation storage unit 870 is “1” (YES in step S202), the processingproceeds to step S203. In a case where the control unit 120 determinesthat the value read from the license information storage unit 870 is not“1” (NO in step S202), the processing is terminated.

In step S203, the control unit 120 issues a command for writing “1” tothe bus switching setting register unit 760 to the input/output controlunit 500. The input/output control unit 500 that has received the writecommand writes “1” to the bus switching setting register unit 760. Thebus switching signal 290 output from the bus switching setting registerunit 760 is input to the bus switching unit 540, and the bus switchingunit 540 switches the bus connected to the bus 280 from the bus 260 tothe bus 270. In the present exemplary embodiment, the control unit 120writes “1” to the bus switching setting register unit 760 via theinput/output control unit 500. Alternatively, the bus switching settingregister unit 760 may be connected to the bus 200 in the imageprocessing unit 860, and the control unit 120 may directly write “1” tothe bus switching setting register unit 760.

In the example described in the fourth exemplary embodiment, the busswitching signal 290 for causing the bus switching unit 540 to executethe switching is generated based on existence of the license informationstored in the license information storage unit 870. According to thefourth exemplary embodiment, there can be provided an advantageouseffect that even without an additional signal terminal in the imageprocessing unit, the path of the ring bus can be changed.

In the fourth exemplary embodiment, there may be a case where eventhough the license information of the extension processing unit 600 hasbeen store in the license information storage unit 870, the extensionprocessing unit 600 is not connected to the extension connector 180 ofthe controller unit 116. In such a case, it is a matter of course thatthe control unit 120 issues a command for displaying a messageindicating that the extension processing unit 600 is not connected tothe extension connector 180 of the controller unit 116, to the operationunit 350. In addition to displaying the message, the path of the ringbus may be switched to the path of buses inside the image processingunit.

In the configurations described in the first and the second exemplaryembodiments, the bus switching unit is provided in the image processingunit. In the configuration described in the third exemplary embodiment,the bus switching unit is provided outside the image processing unit. Inthe method described in the fourth exemplary embodiment, the controlunit in the controller unit controls the bus switching unit, in theconfiguration where the bus switching unit is provided in the imageprocessing unit. In a method described in a fifth exemplary embodiment,the control unit in the controller unit controls a bus switching unit byissuing, when the controller unit is started, a test packet issuecommand, in the configuration where the bus switching unit is providedin the image processing unit.

FIG. 10 is a flowchart illustrating processing for the bus switchingsetting register unit 760 executed by the control unit 120 according tothe fifth exemplary embodiment. In the processing in the fifth exemplaryembodiment, a test packet is output to the ring bus and the ring bus isformed. The configuration of the image forming apparatus is the one inwhich the image processing unit 800 illustrated in FIG. 3 is replacedwith the image processing unit 860 illustrated in FIG. 7, or may be theone same as that illustrated in FIG. 6.

In step S301, the control unit 120 issues a command for writing “1” tothe bus switching setting register unit 760 to the input/output controlunit 500. The input/output control unit 500 that has received the writecommand writes “1” to the bus switching setting register unit 760. As aresult, the bus switching unit 540 connects the bus 240, the bus 250,the bus 260, the output ring bus 210, the buses in the extensionprocessing unit 600, the input ring bus 220, the bus 270, and the bus280 in series in this order so that the ring bus is formed. In a casewhere the extension processing unit 600 is not connected to theextension connector 180, forming of the ring bus fails by disconnectionbetween the output ring bus 210 and the input ring bus 220. In theexemplary embodiment, the control unit 120 writes “1” to the busswitching setting register unit 760 via the input/output control unit500. Alternatively, the switching setting register unit 760 may beconnected to the bus 200 in the image processing unit 860, and thecontrol unit 120 may directly write “1” to the bus switching settingregister unit 760. Alternatively, the initial value in the bus switchingsetting register unit 760 may be set to “1” in advance so that theprocessing in step S301 may be omitted.

In step S302, the control unit 120 issues the test packet transmissioncommand to the input/output control unit 500. The input/output controlunit 500 that has received the test packet transmission command sets theimage processing module A 510, the image processing module B 520, andthe image processing module C 530 to be in a test mode, and transmitsthe test packet to the image processing module A 510.

In step S303, the control unit 120 suspends the processing for apredetermined time period. The predetermined time may be set by the userthrough the operation unit 350. The input/output control unit 500receives the test packet within this time period. The input/outputcontrol unit 500 that has received the test packet writes “1” to a testpacket reception status register (not illustrated). The input/outputcontrol unit 500 that has not received the test packet writes “0” to thetest packet reception status register (not illustrated).

In step S304, the control unit 120 issues a test packet reception statusread command to the input/output control unit 500. The input/outputcontrol unit 500 that has received the test packet reception status readcommand reads a value in the test packet reception status register (notillustrated) which is included in the image processing unit 860. Theinput/output control unit 500 transmits the value thus read to thecontrol unit 120 as a response.

In step S305, the control unit 120 determines whether the test packetreception status value acquired in step S304 is “1”. In a case where itis determined that the test packet reception status value is “1” (YES instep S305), the processing is terminated. In a case where it is notdetermined that the test packet reception status value is “1” (NO instep S305), the processing proceeds to step S306.

In step S306, the control unit 120 issues a command for writing “0” tothe bus switching setting register unit 760 to the input/output controlunit 500. The input/output control unit 500 that has received the writecommand writes “0” to the bus switching setting register unit 760. As aresult, the bus switching unit 540 connects the bus 240, the bus 250,the bus 260, and the bus 280 in series in this order so that the ringbus is formed. In the present exemplary embodiment, the control unit 120writes “0” to the bus switching setting register unit 760 via theinput/output control unit 500. Alternatively, the bus switching settingregister unit 760 may be connected to the bus 200 in the imageprocessing unit 860, and the control unit 120 may directly write “0” tothe bus switching setting register unit 760.

In the example described in the fifth exemplary embodiment, the value inthe bus switching setting register unit 760 is set by using the testpacket and the bus switching signal 290 for causing the bus switchingunit 540 to execute the switching is generated. According to the fifthexemplary embodiment, there can be provided an advantageous effect thateven without an additional signal terminal in the image processing unit,the path of the ring bus can be changed.

According to the exemplary embodiments described above, in theconfiguration in which an extension processing module is connected to aring bus via a connector, the ring bus can be formed even in a casewhere the module is not connected, without attachment of a unit forforming the ring bus. Further, in a case where the module is connectedvia the connector, the path of the ring bus can be switched to the pathincluding the connector.

Other Embodiments

Embodiment(s) can also be realized by a computer of a system orapparatus that reads out and executes computer executable instructions(e.g., one or more programs) recorded on a storage medium (which mayalso be referred to more fully as a ‘non-transitory computer-readablestorage medium’) to perform the functions of one or more of theabove-described embodiment(s) and/or that includes one or more circuits(e.g., application specific integrated circuit (ASIC)) for performingthe functions of one or more of the above-described embodiment(s), andby a method performed by the computer of the system or apparatus by, forexample, reading out and executing the computer executable instructionsfrom the storage medium to perform the functions of one or more of theabove-described embodiment(s) and/or controlling the one or morecircuits to perform the functions of one or more of the above-describedembodiment(s). The computer may comprise one or more processors (e.g.,central processing unit (CPU), micro processing unit (MPU)) and mayinclude a network of separate computers or separate processors to readout and execute the computer executable instructions. The computerexecutable instructions may be provided to the computer, for example,from a network or the storage medium. The storage medium may include,for example, one or more of a hard disk, a random-access memory (RAM), aread only memory (ROM), a storage of distributed computing systems, anoptical disk (such as a compact disc (CD), digital versatile disc (DVD),or Blu-ray Disc (BD)™), a flash memory device, a memory card, and thelike.

While the disclosure has been described with reference to exemplaryembodiments, it is to be understood that the disclosure is not limitedto the disclosed exemplary embodiments. The scope of the followingclaims is to be accorded the broadest interpretation so as to encompassall such modifications and equivalent structures and functions.

This application claims the benefit of Japanese Patent Application No.2015-202719, filed Oct. 14, 2015, and No. 2016-026009, filed Feb. 15,2016, which are hereby incorporated by reference herein in theirentirety.

What is claimed is:
 1. An information processing apparatus comprising: a plurality of processing modules that are connected to each other on a ring bus; a connector for optionally attaching to an extension processing unit; a detection unit configured to detect attachment of the extension processing unit to the connector; and a bus switching unit configured to change, in a case where the detection unit detects the attachment of the extension processing unit, a path of the ring bus in such a manner that an extension processing module in the extension processing unit is connected.
 2. The information processing apparatus according to claim 1, wherein the detection unit configured to detect, upon receiving a first signal, the attachment of the extension processing unit.
 3. The information processing apparatus according to claim 2, wherein the first signal is transmitted from the extension processing unit.
 4. The information processing apparatus according to claim 3, wherein the first signal is transmitted from a bus setting unit through a path that is different from the path of the ring bus.
 5. The information processing apparatus according to claim 2, further comprising a generation unit configured to generate, upon detecting a second signal from the extension processing unit, the first signal.
 6. The information processing apparatus according to claim 5, wherein the second signal is transmitted to the ring bus.
 7. The information processing apparatus according to claim 6, wherein the second signal is a clock signal.
 8. An information processing apparatus comprising: a plurality of processing modules that are connected to each other on a ring bus; a connector for optionally attaching to an extension processing unit; a recording unit configured to record attachment of the extension processing unit to the connector; and a bus switching unit configured to change, in a case where the recording unit has recorded the attachment of the extension processing unit, a path of the ring bus in such a manner that an extension processing module in the extension processing unit is connected.
 9. An information processing apparatus comprising: a plurality of processing modules that are connected to each other on a ring bus; a connector for optionally attaching to an extension processing unit; a checking unit configured to check attachment of the extension processing unit to the connector; and a bus switching unit configured to change, in a case where the checking unit determines that the extension processing unit has been attached, a path of the ring bus in such a manner that an extension processing module in the extension processing unit is connected.
 10. The image processing apparatus according to claim 9, wherein the checking unit is configured to determine, by receiving a test packet transmitted on the ring bus, that the extension processing unit is attached.
 11. A control method for an information processing apparatus to which an extension processing unit is optionally attached, the information processing apparatus including a ring bus and a plurality of processing modules connected to each other on the ring bus, the control method comprising: detecting attachment of the extension processing unit; and changing, in a case where the attachment of the extension processing unit is detected in the detecting, a path of the ring bus in such a manner that an extension processing module in the extension processing unit is connected.
 12. A control method for an information processing apparatus to which an extension processing unit is optionally attached, the information processing apparatus including a ring bus and a plurality of processing modules connected to each other on the ring bus, the control method comprising: recording attachment of the extension processing unit in a recording unit; and changing, in a case where the attachment of the extension processing unit has been recorded in the recording, a path of the ring bus in such a manner that an extension processing module in the extension processing unit is connected.
 13. A control method for an information processing apparatus to which an extension processing unit is optionally attached, the information processing apparatus including a ring bus and a plurality of processing modules connected to each other on the ring bus, the control method comprising: checking attachment of the extension processing unit; and changing, in a case where the extension processing unit is determined to have been attached in the checking, a path of the ring bus in such a manner that an extension processing module in the extension processing unit is connected.
 14. A non-transitory computer readable storage medium storing therein a program for causing a computer to execute a control method for an information processing apparatus to which an extension processing unit is optionally attached, the information processing apparatus including a ring bus and a plurality of processing modules connected to each other on the ring bus, the control method comprising: detecting attachment of the extension processing unit; and changing, in a case where the attachment of the extension processing unit is detected in the detecting, a path of the ring bus in such a manner that an extension processing module in the extension processing unit is connected. 